The invention relates to loop type force transmitting elements made of fiber composite material whereby the loops have a predetermined cross-sectional shape along their lengths. Particularly, the loop may be open at one end and has a constant cross-sectional area along at length but a variable cross-sectional configuration along its length.
Conventional force transmitting elements made of fiber composite material are wound by hand by applying the individual fibers manually around a core which corresponds in its shape to the inner contour of the force transmitting element. At least in the area of the force introduction, the fibers extend in the shape of a loop. Subsequent to the manual winding, the fiber bundle is formed or shaped into the cross-sectional configuration desired for the finished element. The so deformed element is held in this shape or position during the curing. This type of production results, especially in connection with loop elements having a cross-sectional shape which varies along the length of the element, in a nonuniform positioning of the individual fibers which is due to the type of manufacture. Thus, the individual fibers may cross each other at certain points and the fibers are loosely embedded in the fiber bundle without any orderly arrangement. Accordingly, the direction of the fibers in the finished element varies substantially from the stress direction at any local point along the element when the latter is subjected to a load. This variation diminishes substantially the load capacity or strengths of the force transmitting element in view of the anisotropic strengths and stiffness characteristics of fiber composite materials.
Another disadvantage of prior art force transmitting loop elements of fiber composite materials is seen in that their fibers located radially outwardly are loaded relatively little when the element is subject to a load, whereas the fibers located at the inner edge or wall of the element are subjected to high overloads. Such overloads are larger, the larger the ratio is between the outer radius and the inner radius in the looping zone of the force transmitting element. This characteristic of prior art force transmitting loop elements also substantially impairs their load bearing characteristics.